1. Field of the Invention
This disclosure relates to a vacuum interrupter, and particularly, to a vacuum interrupter having a protruding guide unit at a stationary electrode seal cup, capable of guiding alignment of a central arc shielding plate such that the central arc shielding plate can be installed without being biased to one side in a radial direction.
2. Background of the Invention
A vacuum interrupter is an electrical power device in which contacts are contained in a container present in a vacuum state so as to fast extinguish arc, which is generated upon switching on or off an electrical power circuit of high or ultra high voltage. The vacuum interrupter is used in a power station, a substation, an electric power distribution board of a large electrical power consumer or the like by being installed as a core component of a vacuum circuit breaker together with a switching mechanism for switching a movable contact to a closing or opening position, an actuator, a trip controller and the like.
Hereinafter, description will be given of configuration and operation of the vacuum interrupter according to the related art with reference to FIG. 1.
As shown in FIG. 1, a vacuum interrupter includes a stationary electrode 1, a stationary contact 2, a movable contact 4, a movable electrode 3, a ceramic container 8, a stationary electrode cover plate 9, a stationary electrode seal cup 10, a movable electrode cover plate 13, a movable electrode seal cup 7, a bellows 5 and a central arc shielding plate 11.
The related art vacuum interrupter of FIG. 1 may further include a first shielding plate 6 for protection of the bellows 5, a second shielding plate 7a for protection of the bellows 5, and a splash shielding plate 12.
The stationary electrode 1 is a position-fixed electrode and configured as an electrically conductive rod. The stationary electrode 1 may be electrically connected to an electrical power source side of the electrical power circuit (abbreviated as circuit hereinafter).
The stationary contact 2 may be coupled to an end of the stationary electrode 1 by a welding, and can be configured as an electrically conductive disk.
The movable contact 4 is movable to a position of contacting the stationary contact 2 or a position of being separated from the stationary contact 2, and configured as an electrically conductive disk.
The movable electrode 3 supports the movable contact 4 by being welded onto the movable contact 4, and is movable together with the movable contact 4. The movable electrode 3 is formed of an electrically conductive material, and may be electrically connected to an electrical load side of the circuit.
The ceramic container 8 is an enclosure for receiving the stationary contact and the movable contact 4 therein, and has a tubular shape having upper and lower portions open.
The stationary electrode cover plate 9 is an annular member which is installed at a side of the stationary electrode 1 and has a central through hole for allowing the stationary electrode 1 to be inserted therethrough. The stationary electrode cover plate 9 seals the upper or lower open portion of the ceramic container 8.
The stationary electrode seal cup 10 is connected to seal a gap between the ceramic container 8 and the stationary electrode cover plate 9. The stationary electrode seal cup 10 may be made of a metal which has one side section in a shape similar to alphabet “L” and has an annular shape as a whole. The stationary electrode seal cup 10 may be connected to the ceramic container 8 and the stationary electrode cover plate 9, respectively, in a welding manner.
The movable electrode cover plate 13 is installed at a side of the movable electrode 3, and is an annular member which has a central through hole whose diameter is greater than an outer diameter of the movable electrode 3 for allowing an axial movement of the movable electrode 3. The movable electrode cover plate 13 seals an upper or lower open portion of the ceramic container 8.
The movable electrode seal cup 7 is a member connected to seal a gap between the ceramic container 8 and the movable electrode cover plate 13. The movable electrode seal cup 7 may be made of a metal which has one side section in a shape similar to alphabet “L” and has an annular shape as a whole. The movable electrode seal cup 7 may be connected to the ceramic container 8 and the movable electrode cover plate 13, respectively, in a welding manner.
The bellows 5 is a member whose both ends are connected to the movable electrode cover plate 13 and the movable electrode 3, respectively, for sealing a gap between the movable electrode cover plate 13 and the movable electrode 3. The bellows 5 has a plurality of metallic wrinkles so as to be expandable and contractible in response to the axial movement of the movable electrode 3.
The central arc shielding plate 11 is a shielding plate fixed between the ceramic container 8 and the contacts, namely, the stationary contact 2 and the movable contact 4 so as to shield arc, which is generated between the stationary contact 2 and the movable contact 4 upon switching on or off the contacts, from being delivered directly toward an inner wall of the ceramic container 8.
The first shielding plate 6 for protection of the bellows 5 is a shielding plate, which has a “U”-like longitudinal section and is in a tubular shape with upper and lower sides open. One open end of the first shielding plate 6 is connected to the movable electrode 3 in the welding manner so as to shield a portion of the bellows 5, which is adjacent to the movable contact 4, protecting the corresponding portion from arc at the outside of the bellows 5.
The second shielding plate 7a for protection of the bellows 5 is a metal member which has a side section in a hook-like shape and has an annular shape as a whole. The second shielding plate 7a may have one end portion welded onto the movable electrode seal cup 7 and another end portion extending from the one end portion toward the movable contact 4 at the outside of the bellows 5.
The splash shielding plate 12 is a disk-like metal plate having a central through hole for allowing an end portion of the movable electrode 3 to be inserted therethrough. The splash shielding plate 12 may be welded onto the end portion of the movable electrode 3 and shield a rear side of the movable electrode 3 and a portion near one side of the bellows 5 so as to protect them from metallic vapor generated due to arc.
Hereinafter, detailed description will be given of configuration and method for installing the central arc shielding plate according to the related art with reference to FIGS. 2 and 3.
The central arc shielding plate 11 according to one embodiment of the related art, as shown in FIG. 2, is closely adhered onto the stationary electrode seal cup 10 on the stationary electrode cover plate 9 and welded thereonto for installation.
However, in the installation method for the central arc shielding plate 11 according to the one embodiment of the related art, there is not any member provided for guiding the central arc shielding plate 11 to be installed without being biased to one side on the stationary electrode cover plate 9 in a radial direction. This may make it difficult to align the central arc shielding plate 11 upon installation thereof.
Also, the related art central arc shielding plate 11 according to another embodiment, as shown in FIG. 3, is closely adhered onto an alignment plate 14 after the alignment plate 14 is installed on the stationary electrode cover plate 9, and then welded thereonto for installation.
In the installation method for the central arc shielding plate 11 according to the another embodiment of the related art, the additional component, namely, the alignment plate 14, is required. This causes several problems, such as an increase in fabrication costs for the vacuum interrupter due to the increase in the number of components, lowering of productivity due to an additional fabrication process, an increase in portions to be welded, and an increase in defectively welded portions.